A large, community-based study suggested that over 19% of school-age children have tic disorders;[9] the children with tic disorders in that study were usually undiagnosed.

As many as 1 in 100 people may experience some form of tic disorder, usually before the onset of puberty.[10] Tourette syndrome is the more severe expression of a spectrum of tic disorders, which are thought to be due to the same genetic vulnerability. Nevertheless, most cases of Tourette syndrome are not severe. Although a significant amount of investigative work indicates genetic linkage of the various tic disorders, further study is needed to confirm the relationship.[11]